[PATCH] iommu: Add device name to iommu map/unmap trace events

From: Sai Prakash Ranjan
Date: Tue Feb 09 2021 - 07:37:34 EST


IOMMU map/unmap traces become hard to decode i.e., it becomes hard
to associate the map/unmap events with the particular device from
the iova/paddr/size parameters alone when there are multiple
devices attached. So it is useful to add the device name to iommu
trace events which can be used to filter out map/unmap traces for
a particular device when we are debugging iommu faults such as
context faults where we are interested with the map/unmap traces
for a specific device.

Before:
map: IOMMU: iova=0x0000000ffff36000 paddr=0x00000001164d8000 size=4096
unmap: IOMMU: iova=0x0000000ffff36000 size=4096 unmapped_size=4096

After:
map: IOMMU: dev=1d84000.ufshc iova=0x0000000fffa88000 paddr=0x00000001063db000 size=4096
unmap: IOMMU: dev=1d84000.ufshc iova=0x0000000fffa88000 size=4096 unmapped_size=4096

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
drivers/iommu/iommu.c | 8 +++++---
include/linux/iommu.h | 1 +
include/trace/events/iommu.h | 20 ++++++++++++--------
3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index d0b0a15dba84..37081b745f38 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1947,8 +1947,10 @@ static int __iommu_attach_device(struct iommu_domain *domain,
return -ENODEV;

ret = domain->ops->attach_dev(domain, dev);
- if (!ret)
+ if (!ret) {
trace_attach_device_to_domain(dev);
+ strscpy(domain->dev_name, dev_name(dev), sizeof(domain->dev_name));
+ }
return ret;
}

@@ -2440,7 +2442,7 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
if (ret)
iommu_unmap(domain, orig_iova, orig_size - size);
else
- trace_map(orig_iova, orig_paddr, orig_size);
+ trace_map(orig_iova, orig_paddr, orig_size, domain->dev_name);

return ret;
}
@@ -2523,7 +2525,7 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
unmapped += unmapped_page;
}

- trace_unmap(orig_iova, size, unmapped);
+ trace_unmap(orig_iova, size, unmapped, domain->dev_name);
return unmapped;
}

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e7fe519430a..6064187d9bb6 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -87,6 +87,7 @@ struct iommu_domain {
void *handler_token;
struct iommu_domain_geometry geometry;
void *iova_cookie;
+ char dev_name[32];
};

enum iommu_cap {
diff --git a/include/trace/events/iommu.h b/include/trace/events/iommu.h
index 72b4582322ff..44e48fb8b677 100644
--- a/include/trace/events/iommu.h
+++ b/include/trace/events/iommu.h
@@ -85,47 +85,51 @@ DEFINE_EVENT(iommu_device_event, detach_device_from_domain,

TRACE_EVENT(map,

- TP_PROTO(unsigned long iova, phys_addr_t paddr, size_t size),
+ TP_PROTO(unsigned long iova, phys_addr_t paddr, size_t size, const char *dev_name),

- TP_ARGS(iova, paddr, size),
+ TP_ARGS(iova, paddr, size, dev_name),

TP_STRUCT__entry(
__field(u64, iova)
__field(u64, paddr)
__field(size_t, size)
+ __string(dev_name, dev_name)
),

TP_fast_assign(
__entry->iova = iova;
__entry->paddr = paddr;
__entry->size = size;
+ __assign_str(dev_name, dev_name);
),

- TP_printk("IOMMU: iova=0x%016llx paddr=0x%016llx size=%zu",
- __entry->iova, __entry->paddr, __entry->size
+ TP_printk("IOMMU: dev=%s iova=0x%016llx paddr=0x%016llx size=%zu",
+ __get_str(dev_name), __entry->iova, __entry->paddr, __entry->size
)
);

TRACE_EVENT(unmap,

- TP_PROTO(unsigned long iova, size_t size, size_t unmapped_size),
+ TP_PROTO(unsigned long iova, size_t size, size_t unmapped_size, const char *dev_name),

- TP_ARGS(iova, size, unmapped_size),
+ TP_ARGS(iova, size, unmapped_size, dev_name),

TP_STRUCT__entry(
__field(u64, iova)
__field(size_t, size)
__field(size_t, unmapped_size)
+ __string(dev_name, dev_name)
),

TP_fast_assign(
__entry->iova = iova;
__entry->size = size;
__entry->unmapped_size = unmapped_size;
+ __assign_str(dev_name, dev_name);
),

- TP_printk("IOMMU: iova=0x%016llx size=%zu unmapped_size=%zu",
- __entry->iova, __entry->size, __entry->unmapped_size
+ TP_printk("IOMMU: dev=%s iova=0x%016llx size=%zu unmapped_size=%zu",
+ __get_str(dev_name), __entry->iova, __entry->size, __entry->unmapped_size
)
);

--
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